Diameter Of Nanospheres Research Articles

Mie Resonator Color Inks of Monodispersed and Perfectly Spherical Crystalline Silicon Nanoparticles

AbstractA crystalline silicon (Si) nanoparticle (NP) of 100–200 nm in diameter exhibits a highly saturated color owing to Mie resonance, and can be a component to realize angle‐insensitive structural color covering the entire visible range. However, to date, coloring a substrate by Si nanostructures has only been achieved in a very small area by using electron beam lithography and dry etching processes. In this work, a Si NP color ink capable of coloring a flexible substrate by a painting process is developed. The sphericity of Si NPs is very high; the circularity factor obtained from a transmission electron microscope image reaches 0.97. The average diameter of Si nanospheres is controlled from 95 to 200 nm, and the polydispersity defined by the standard deviation divided by the average diameter is as small as 6%. Because of the high sphericity, high crystallinity, high size purity, and perfect dispersion in solution, the Si nanosphere solutions exhibit vivid colors recognizable by naked eye in a range of blue to orange. The Si nanosphere color inks combined with a polymer binder are capable of coloring flexible substrates by a painting process.

Continuous roll-to-roll patterning of three-dimensional periodic nanostructures

In this work, we introduce a roll-to-roll system that can continuously print three-dimensional (3D) periodic nanostructures over large areas. This approach is based on Langmuir-Blodgett assembly of colloidal nanospheres, which diffract normal incident light to create a complex intensity pattern for near-field nanolithography. The geometry of the 3D nanostructure is defined by the Talbot effect and can be precisely designed by tuning the ratio of the nanosphere diameter to the exposure wavelength. Using this system, we have demonstrated patterning of 3D photonic crystals with a 500 nm period on a 50 × 200 mm2 flexible substrate, with a system throughput of 3 mm/s. The patterning yield is quantitatively analyzed by an automated electron beam inspection method, demonstrating long-term repeatability of an up to 88% yield over a 4-month period. The inspection method can also be employed to examine pattern uniformity, achieving an average yield of up to 78.6% over full substrate areas. The proposed patterning method is highly versatile and scalable as a nanomanufacturing platform and can find application in nanophotonics, nanoarchitected materials, and multifunctional nanostructures.

A highly sensitive laser focus positioning method with sub-micrometre accuracy using coherent Fourier scatterometry

We report a novel method of focus determination with high sensitivity and submicrometre accuracy. The technique relies on the asymmetry in the scattered far field from a nanosphere located at the surface of interest. The out-of-focus displacement of the probing beam manifests itself in imbalance of the signal of the differential detector located at the far field. Up–down scanning of the focussed field renders an error S-curve with a linear region that is slightly bigger than the corresponding vectorial Rayleigh range. We experimentally show that the focus can be determined not only for a surface with high optical contrast, such as a silicon wafer, but also for a weakly reflecting surface, such as fused silica glass. Further, for the probing wavelength of 405 nm, three sizes of polystyrene latex spheres, namely 200, 100, and 50 nm in diameter, are tested. Higher sensitivity was obtained as the sphere diameter became smaller. However, due to the fact that the scattering cross-section decreases as the sixth power of the nanosphere diameter, we envision that further size reduction of the studied sphere would not contribute to a drastic improvement in sensitivity. We believe that the proposed method can find applications in bio/nano detection, micromachining, and optical disk applications.

Tracking and Analyzing the Brownian Motion of Nano-objects Inside Hollow Core Fibers.

Tracking and analyzing the individual diffusion of nanoscale objects such as proteins and viruses is an important methodology in life science. Here, we show a sensor that combines the efficiency of light line illumination with the advantages of fluidic confinement. Tracking of freely diffusing nano-objects inside water-filled hollow core fibers with core diameters of tens of micrometers using elastically scattered light from the core mode allows retrieving information about the Brownian motion and the size of each particle of the investigated ensemble individually using standard tracking algorithms and the mean squared displacement analysis. Specifically, we successfully measure the diameter of every gold nanosphere in an ensemble that consists of several hundreds of 40 nm particles, with an individual precision below 17% (±8 nm). In addition, we confirm the relevance of our approach with respect to bioanalytics by analyzing 70 nm λ-phages. Overall these features, together with the strongly reduced demand for memory space, principally allows us to record thousands of frames and to achieve high frame rates for high precision tracking of nanoscale objects.

Transition from discrete patches to plasmonic nanohole array by glancing angle deposition on nanosphere monolayers

By combining nanosphere lithography and glancing angle deposition, a morphological transition from disconnected patchy silver (Ag) coated nanosphere particles to a connected Ag nanohole sheet on close-packed nanosphere monolayers has been demonstrated, which significantly changes the optical property of the Ag nanostructure deposited. For different sized nanosphere monolayers, when the vapor incident angle was set to be 55°, the transmission spectra showed complicated features when the Ag deposition thickness was less than 60 nm. When the thickness was large enough (≥60 nm), a distinguished extraordinary optical transmission (EOT) peak was observed. The EOT peak wavelength position is independent of the Ag thickness deposited and is proportional to the nanosphere diameter. The obtained EOT peaks possess a high quality factor and have high transmission values compared to those reported in the literature for similar structures. The Monte Carlo growth simulations demonstrate the morphological transition from the patchy arrays to nanohole arrays while the electromagnetic numerical calculations confirm the change in the optical properties. Such a high quality EOT response could be used for constructing better sensors or developing other plasmonic applications.

Selective excitation and enhancement of multipolar resonances in dielectric nanospheres using cylindrical vector beams

Resonant excitation and manipulation of complex interactions among two or more resonances in high-index dielectric nanostructures provide great opportunities for engineering novel optical phenomena and applications. However, difficulties often arise when interpreting the observed spectra because of the overlap of the broad resonances contributed by many factors such as particle size, shape, and background index. Therefore, selective excitation of resonances that spectrally overlap with each other provides a gateway towards an improved understanding of the complex interactions. Here, we demonstrate selective excitation and enhancement of multipolar resonances of silicon nanospheres using cylindrical vector beams (CVBs) with different diameters of nanospheres and numerical apertures (NAs) of the excitations. By combining single particle spectroscopy and electrodynamic simulations, we show that the radially polarized beam can selectively excite the electric multipoles, whereas the azimuthally polarized beam can selectively excite the magnetic multipoles even though multipolar resonances are convoluted together due to their spectral overlap. Moreover, focusing the CVBs with high NA can lead to a dominant longitudinal polarization of the electric or magnetic field. We show that the enhanced longitudinal polarization with increasing NA of the radially and azimuthally polarized beams can selectively enhance the electric and magnetic multipolar resonances, respectively. Our approach can be used as a spectroscopy tool to enhance and identify multipolar resonances leading to a better understanding of light-matter interactions in other dielectric nanostructures as well as serve as a first step toward excitation of dark mode and Fano resonances in dielectric oligomers by breaking the symmetry of the nanostructures.

Yolk-double shell Fe3O4@C@C composite as high-performance anode materials for lithium-ion batteries

Herein, yolk-double shell Fe3O4@C@C nanospheres (YDS-FCCNs) were designed and synthesized via solvothermal and following heat management. The as-obtained yolk-shell morphology consisted by two parts: one for the Fe3O4@C nanosphere (diameter about 100 nm) as core, and the other for nitrogen-doped carbon (thickness about 50 nm) as the shell. The YDS-FCCNs composite exhibited preeminent cycling stability of 780 mAh/g at 0.5 A/g after 500 cycles, even at higher current density of 2 A/g, it still retained a reversible capacity of 559 mAh/g after 500 cycle. The good electrochemical performance could attribute to the following factors: First, the hierarchical double carbon shell could prevent the agglomeration of the Fe3O4, meanwhile largely enhance the electrical conductivity. Second, the synergistic effects for multilayered structure and atomic doping could improve the comprehensive electrochemical performance.

Effects of different structural parameters and the medium environment on plasmonic lattice resonance formed by Ag nanospheres on SiO2 nanopillar arrays

The effects of the diameter of SiO2 nanopillars, the diameter of Ag nanospheres, the arrays’ period, and the medium environment on the plasmonic lattice resonance (PLR) formed by Ag nanospheres on SiO2 nanopillar arrays are systematically investigated. Larger diameters of SiO2 nanopillars with other parameters kept constant will widen the PLR peak, redshift the PLR wavelength, and weaken the PLR intensity. Larger diameters of Ag nanospheres with other parameters kept constant will widen the PLR peak, redshift the PLR wavelength, and strengthen the PLR intensity. Larger array periods or larger refractive index of medium environment corresponds to larger PLR wavelengths.

Fabrication and ultraviolet-visible-near infrared absorption properties of silver nano arrays based on aluminum

In this paper, the highly ordered periodic silver nanosphere arrays are fabricated by vacuum evaporation based on anodic aluminum oxide (AAO) template. The diameter and spacing of silver nanosphere in the arrays are adjusted just by controlling the thickness of evaporation. Furthermore, this can effectively modulate the absorption peaks and bandwidths in ultraviolet-visible-near-infrared regions. The measurement results of absorption spectra show that the nano-arrays have obvious electromagnetic wave absorption characteristics in the ultraviolet, visible and near-infrared bands. The finite-difference time-domain theoretical simulation combined with experiments is used to analyze the physical mechanism of light absorption characteristics in different wavebands. The ultraviolet strong absorption is due to the Fano resonance induced by asymmetric dielectric environment of silver and aluminum; the visible absorption originates from local surface plasmon resonance of silver nanoparticles; the near-infrared strong absorption is attributed to the surface lattice resonance of silver nanosphere arrays.

Broadband anti-reflection in Si substrate via Ag nanospheres on Si nanopillar arrays

A structure of Ag nanospheres on Si nanopillar arrays which sit on a Si substrate is presented to obtain a broadband low reflection. The simulated results show that the average reflection can reach 2.66% in the wavelength range of 400–1100 nm due to the forward scattering effects of Ag nanospheres and the antireflective effects of Si nanopillars, much lower than that of Ag nanosphere arrays on Si substrates and that of Si nanopillar arrays on Si substrates. The diameter of Ag nanospheres, the period of the arrays, the diameter and height of Si nanopillars have important influences on the reflection. This work provide a practicable method for the optimization of anti-reflection in different device applications.

Amorphous liquid phase induced synthesis of boron nitride nanospheres for improving sintering property of h-BN/ZrO2 composites

Hexagonal boron nitride (BN) nanospheres with large quantities and high crystallinity have been successfully synthesized from BxCyNzOkHl precursors without any catalyst. The uniform size of the obtained BN nanospheres is about 20 nm. The structure, morphology and surface chemical property of the products were characterized using XRD, FTIR, SEM, HRTEM and XPS. The results show that BN nanospheres with good crystallinity are prepared by heat treatment of amorphous BxCyNzOkHl precursor at 1100 °C in flowing N2. The urea content has great influence on the crystallinity and morphology of BN nanospheres. The diameter and morphology of BN nanospheres dramatically vary at different temperature. Based on the amorphous liquid phase encapsulated induce model, the reaction mechanism and morphological evolution mechanism were described. The viscous liquid containing B and N amorphous phase plays a crucial role in the formation of BN nanospheres. The BN nanospheres improved the density of h-BN/ZrO2 composites from 94.43% to 97.02%.

A Cu(II) Indicator Platform Based on Cu(II) Induced Swelling that Changes the Extent of Fluorescein Self-Quenching.

In this study, we established a new fluorescent indicator platform. The responsive element consists of poly(N-isopropylacrylamide) nanospheres that include small percentages of fluorescein and a ligand, anilinodiacetate (phenylIDA). Nanosphere diameters were determined to be in the range from 50 to 90 nm by scanning electron microscopy. They were entrapped in a polyacrylamide gel to prevent nanosphere aggregation. At pH 6, the ligand is negatively charged in the absence of metal ions. Charge-charge repulsion causes the nanosphere to swell. Dynamic light scattering measurements show that these nanospheres do not shrink and aggregate at high temperature. Cu(II) binding neutralizes the charge causing the particles to shrink. This brings fluoresceins closer together, increasing the degree of self-quenching. The intensity decreases by 30% as Cu(II) concentration increases. To rule out the possibility that the observed decrease in intensity was due to Cu(II) quenching of fluorescence, we also added Zn(II) and observed a decrease in intensity. This approach can be adapted to sense different metal ions and different concentrations of Cu(II) by changing the ligand.

Synthesis of NiO-In2O3 heterojunction nanospheres for highly selective and sensitive detection of ppb-level NO2

NiO-In2O3 composite nanospheres with p-n heterojunction structure were fabricated by a one-step hydrothermal method. A series of XRD, FTIR, SEM, TEM, and XPS measurements were utilized to characterize the morphology and structure of NiO-In2O3 composite nanospheres, accompanying with pure In2O3 nanospheres for comparison. The results indicated that both the diameters of pure In2O3 and NiO-In2O3 nanospheres were in the range of 400–500 nm, indicating that the introduction of Ni did not change the product morphology. The gas sensing performance showed that Ni functionalization with proper content was conducive to enhancing NO2 sensing performance compared with pure In2O3 nanospheres. The obtained NiO-In2O3 composite nanospheres showed excellent response-recovery properties to NO2 gas and high selectivity, stability, and repeatability. The highest response of 1771 was achieved for 10% NiO-In2O3 composite nanospheres to 10 ppm NO2 gas at 100 °C, and the corresponding response to 10 ppb NO2 gas was 1.2. The gas sensing mechanism of NiO-In2O3 composite nanospheres to NO2 gas was discussed based on the electron depletion theory and the formation of p-n heterojunction structure. The results show that NiO-In2O3 composite nanospheres have favorable potential application in ppb-level NO2 detection.

Preparation and Characterization of CuO-TiO₂ Composite Hollow Nanospheres with Enhanced Photocatalytic Activity Under Visible Light Irradiation.

CuO-TiO₂ composite hollow nanospheres were synthesized using polystyrene as a template. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize the average diameter, shell thickness, crystalline structure, and composition of CuO-TiO₂ composite hollow nanospheres. UV-vis absorption spectrum was used to measure the optical absorption property of the CuO-TiO₂ composite hollow nanospheres. The photocatalytic performance of the samples was characterized by degrading 10 mg·L-1 methylene blue under visible light irradiation. The results showed that the CuO-TiO₂ composite hollow nanospheres exhibited better photocatalytic performance than the pure TiO₂ nanoparticles and TiO₂ hollow nanospheres. The improvement in photocatalytic performance was attributed to the enhanced light absorption in the visible light region.

A dopamine-imprinted chitosan Film/Porous ZnO NPs@carbon Nanospheres/Macroporous carbon for electrochemical sensing dopamine

Dopamine (DA) is a nerve-transducing chemical that helps cells transmit pulses. Too high or too low concentration of DA is detrimental to human health. Therefore, finding a fast, efficient and sensitive method for detecting DA is of great significance. Here, a DA-imprinted chitosan (CS) film/ZnO nanoparticles (NPs)@carbon (C)/three-dimensional kenaf stem-derived macroporous carbon (3D-KSC) was prepared for electrochemical detection of DA. The DA-imprinted CS film/ZnO NPs @C/3D-KSC was prepared by growing zeolite imidazole framework-8 (ZIF-8) on 3D-KSC, carbonizing under N2 atmosphere, electrodepositing AA-CS on ZnO NPs@C/3D-KSC and eluting template AA molecules. The results showed that ZIF-8 derived porous ZnO NPs@C nanospheres were arranged evenly on 3D-KSC surface to form a monolayer. The diameter of nanospheres was approximately 500–600 nm, and the nanospheres were composed of ZnO NPs embedded in porous carbon. A layer of CS with DA-imprinted pores was covered on the ZnO NPs@C nanospheres, so the DA-imprinted CS film/ZnO NPs@C/3D-KSC integrated electrode exhibited better selectivity for DA detection. The linear range was 0.12 nM-152 μM, the detection limit was 0.039 nM, and the sensitivity was 757 μA mM−1 cm-2. The DA-imprinted CS film/ZnO NPs@C/3D-KSC integrated electrode also showed higher stability.

Development and characterization of PLGA nanoparticles containing 1,3-dihydroxy-2-methylxanthone with improved antitumor activity on a human breast cancer cell line

Interest on xanthones has been growing considerably due to their broad spectrum of biological activities. 1,3-Dihydroxy-2-methylxanthone (DHMXAN) showed a significant inhibitory effect on the growth of MCF-7 cancer cells. DHMXAN-loaded nanosphere and nanocapsule formulations were prepared by the solvent displacement technique with the aim of improving the delivery of this poorly water-soluble compound. Moreover, we investigated the usefulness of this nanotechnology-based approach on the improvement of compound’s antitumor activity. Nanosphere and nanocapsule mean diameters ranged from 117 ± 8 to 138 ± 5 nm and from 266 ± 7 to 286 ± 22 nm, respectively, and both systems exhibited negative surface charge. Incorporation efficiency values of DHMXAN in nanospheres and nanocapsules were higher than 30% (30.9 ± 3.3 to 38.8 ± 3.6%) and 80% (85 ± 7 to 88 ± 6%), respectively. The release study of DHMXAN from nanocapsules suggests that drug release is mainly governed by its partition between the oil core and the external aqueous medium. The effect of different nanoparticulate formulations on the growth of human breast cancer cell line MCF-7 was evaluated using the sulforhodamine B (SRB) assay. Incorporation of DHMXAN in nanospheres and nanocapsules afforded a marked potentiation of the compound inhibitory effect.

Reactive dye/poly(styrene-co-butyl acrylate-co-trimethyl(vinylbenzyl) ammonium chloride) nanospheres with high coloration performance for cleaner dyeing of cotton fabrics

The low utilization of dyestuff in textile coloration leads to serious environmental pollution and wasting of resources. Dye/polymer nanospheres have high absorbing, reflecting and scattering light properties due to the large specific surface area, the regular shape, and the uniform size. In the present study, we report the reactive dye/poly(styrene-butyl acrylate-trimethyl ammonium chloride) composite nanosphere as a highly efficient colorant for cationic cotton fabrics. The dye contents of the four colored nanospheres can reach to 217–404 mg/g. The hydration diameters of the composite nanospheres are 83–101 nm for four different reactive dyes. They have the negative zeta potentials, approximately − 25.3 to − 37.6 mV. The reactive dye/copolymer nanospheres exhibit much more powerful coloration ability for cotton fabrics and higher dye utilization than the ordinary reactive dyes. The color depths of cotton fabrics dyed with colored nanospheres are 2.8, 4.9, 10.6 and 4.2 times of the values of the corresponding dye colored samples. The dye/copolymer nanospheres have much larger color gamut than the ordinary dyes. The color durability and levelness of the dye/copolymer nanospheres on cotton fibers are good enough for practical applications. What’s more important is that the residual dye/copolymer nanospheres in the dye bath can be reused in the next dyeing process. This novel nanosphere dyeing method does not only save the colorants but also avoid the discharging of colored sewage. The reactive dye/poly(St-BA-VBT) nanospheres were successfully fabricated by adding the cationic poly(St-BA-VBT) nanospheres dispersions into reactive dye solutions. This article offered a novel dyeing method for cotton fabrics using dye/poly(St-BA-VBT) nanospheres. These colored nanospheres can endow the cotton fabrics with good color performance and avoid the discharging of colored waste water, which provide a green way for textile coloration.

Cu–Co bimetallic nanospheres embedded in graphene as excellent anode catalysts for electrocatalytic oxygen evolution reaction

In this work, novel Cu–Co bimetal/reduce graphene oxide nanostructures with excellent catalytic activity were prepared by embedding Cu–Co bimetallic nanospheres into the interlayer of graphene. The composite materials were characterised by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) etc. The characterisation results indicated that the diameters of the bimetallic nanospheres were controlled within ∼60 nm, which embedded uniformly in graphene. A series of electrochemical tests were carried out and the composites were found to exhibit excellent oxygen evolution properties under alkaline conditions. The excellent catalytic activity and stability make the composite have great potential for wide application and provide a basis for its industrial application.

Ultrasmall self-assembly poly(N-isopropylacrylamide-butyl acrylate) (polyNIPAM-BA) thermoresponsive nanoparticles

Reported poly(N-isopropylacrylamide) (poly(NIPAM)) thermoresponsive systems do not preserve their structure and shape regardless applied temperature. Poly(NIPAM) modified with lipophilic units of butylacrylate (BA) is expected to form spontaneously nanospheres stable at a broad range of temperature. Moreover, it should be possible to introduce solvatochromic dyes to the spheres for optical evaluation of the system and designing thermometers at the nanoscale.In this study, poly(NIPAM-BA) polymer used in nanoprecipitation process formed stable nanospheres, as shown by scanning transmission electron microscopy (STEM), dynamic light scattering (DLS), and zeta potential analysis. As a model compound, Nile Red was introduced to the structures allowing fluorometric investigation and confocal imaging. The nanoparticles were stable in solution both below and above polymer transition temperature. However, as expected for thermoresponsive polymer, the diameter of nanospheres changed from about 30 nm at 10 °C to about 150 nm at 20 °C. For dye loaded spheres this process was coupled with pronounced change in emission. For low temperatures nanostructures existed as ultra-small highly lipophilic particulates, whereas at higher temperatures their diameter and hydrophilicity increased. In consequence the dye was extruded from spheres at low temperatures as a shell layer, this process was fully reversible within the temperatures range from 5 to 30 °C. Freezing of the nanospheres resulted in irreversible change in morphology allowing monitoring of transient sample freezing. Forming poly(NIPAM-BA) spheres loaded with solvatochromic dyes were found as a facile technique for designing optical nanothermometer.

DEVELOPMENT OF AN AUTOMATED METHOD TO PERFORM A QUANTITATIVE STUDY OF PARTICLE SIZE DISTRIBUTION AND THE EFFECT OF A CONDUCTIVE LAYER IN SCANNING ELECTRON MICROSCOPY

The determination of particle size distribution is an important parameter for controlling industrial processes, particularly in the field of pharmaceuticals. It is also an important parameter for characterizing nanoparticles. The best technique for determining particle size distribution is scanning electron microscopy. The process of counting particles is typically performed manually, which requires both more time and a higher standard deviation than automatic methods. This study shows the results of a particle counting procedure that relies on a fully automated method that was found to improve the reproducibility of the measurement. The effect on the diameter of near-spherical polymer nanospheres between 20 and 100 nm (mean of 60 nm) when samples were coated by a conducting layer (such as gold or carbon) was also evaluated. The images were collected using a field emission scanning electron microscope and then processed using the ImageJ program. Results showed that the method proposed in this work produces mean diameter values in accordance with NIST-traceable near-spherical polymer nanospheres for the sample without coating. The study also revealed two main effects of the conductive coating: changes to topography and an increase in mean particle diameter.